1 Ethernet port and 2 DHCP ranges

I've got a 1721 12.3(10) that I need to have DHPC going to 192.168.2.x and

192.168.12.x ranges (having outgrown a single class C and neither .1 nor .3 is available) The primary ip address of F0 is

I tried to use the commnd - ip address secondary - which worked for routing purposes but I can only get DHCP address from the .2 scope. Is there a way to get DHCP from both scopes using the single Ethernet interface?

Thank you

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Since your are using DHCP then move to a diifernet address range where you can use a /23 block

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This scenario makes it difficult (impossible) for the DHCP server to know what address range to assign to a client. There needs to be someway to accomplish this. If you had different vlans trunking to a switch and clients resided on the different vlans, that is a way. However, with simply a multihomed interface you can not. You need to expand your address range, as Merv noted. This is what I would do....

Expand the range to a /22 ( Assign a range for static addresses (192.168.2 for example), assign a range for DHCP ( for example) and leave the rest for future growth that you can apply as static or DHCP in the future.

Hope that helps,


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Assuming you are using an ip-helper address to relay DHCP requests to your server, you also need to configure "ip dhcp smart-relay".

Without it the router will only use the primary interface ip address in the giaddr field. With it, the router will start to use the secondary address once it stops getting replies to requests sent using the promary address.

You don't have any/much control over which subnet any given host will end up in, other than statically assigning them.

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Martin Gallagher

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